The unifying hypothesis of our "Cytokine Gene Therapy (CGT) of Cancer: Preclinical Studies" PPG is that the transfer of cytokine genes into the tumor microenviroment will promote enhanced recruitment, diversity, function, and maintenance of cellular anti-tumor immunity. When properly applied, CGT will be effective in promoting tumor regression in both the periphery and the brain and result in prolonged anti-tumor protection, principally mediated by Type-1 effector T ceils. The understanding of the immunobiology underlying the efficacy of of CGT on the afferent and efferent arms of the anti-tumor response will provide major cues for the ultimate translation of those most promising CGT applications into clinical trials for the treatment of patients with diverse forms of cancer. Importantly, our studies will be applied to two clinically-relevant model systems that reflect human disease; 1) spontaneously metatasizing subcutaneous melanomas that disseminate to lungs, liver and brain and which are frequently lethal in advanced disease stage patients, and 2) intracranial melanoma and glioma models that mimic human disease where lethality is common and few treatment options are currently available. We propose three pro-clinical projects that will evalute the impact of single-modality and combinational CGT on both the induction phases of tumor immunity and the fortification of the effector phases of "clinically relevant" immunity within the tumor microenvironment conditioned by CGT. We have chosen the specific cytokines for appication in CGT approaches based on their abilities to promote and sustain Type-1 immunity, to enhance leukocyte infiltrate into tumor lesions and to facilitate tumor antigen-specific crosspresentation. Combinational cytokine gene therapy approaches will be selected for evaluation based on the known or hypothesized immunobiologic synergy of the selected modalities (including both dendritic cell-based vaccines and cytokine GT) and cytokines in promoting therapeutic Type-1 immunity. This highly-integrated effort, if successful, will provide the basis for developing innovative, safe and effective CGT approaches for cancer. Our 3 Projects are: Project 1. DC-Based Cytokine Gene Immunotherapy for Central Nervous System (CNS) Tumors; Project 2. IL-12 Gene Therapy to Prime and Repolarize Anti-Tumor Th1-type T cells and enhance Epitope Spreading; Project 3. IL-18 and IL-1 H4 gene therapy to promote innate and specific tumor immunity.